Relaxation Method Applied to LOFARGRAM

Abstract

The term LOFAR is defined as 'search technique using omnidirectional sonobuoys'. It is an acronym for Low Frequency Analysis and Recording. When the signal to noise ratio is low, the detection of a track in a lofargram by computer is difficult. Actually, operators often face this kind of problem when detecting an acoustic signature in the noisy sea environment. Furthermore, operators must keep on tracking lofargram to identify a given target. This problem could be handled by the automation of lofargram processing using filtering or image processing techniques. This technique will suppress the background and emphasize the spectral lines in the lofargram. Targets can be tracked by an automatic lofargram processing system up to a certain point at which the system should alarm the operator. The enhancement processing of lofargrams using a relaxation method could be one part of the automatic system of lofargram processing to provide available target information for good decisions. The objective of this thesis is to enhance spectral lines of the lofargram by using the relaxation method which is an iterative approach to line detections.

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Document Details

Document Type
Technical Report
Publication Date
Jun 01, 1990
Accession Number
ADA237342

Entities

People

  • Y. H. Yang

Organizations

  • Naval Postgraduate School

Tags

Communities of Interest

  • Ground and Sea Platforms
  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Acoustics
  • Algorithms
  • Automatic
  • Change Detection
  • Computers
  • Detection
  • Detectors
  • Frequency
  • Image Processing
  • Noise
  • Passive Sonar
  • Pattern Recognition
  • Probability
  • Spectra
  • Spectral Lines
  • Two Dimensional
  • Warning Systems

Fields of Study

  • Engineering

Readers

  • Acoustical Oceanography.
  • Computer Vision.
  • Finite Element Method (FEM) for solving Partial Differential Equations (PDEs)